What are the activation modes of activity? What does it mean? (three)

FLAG_ACTIVITY_NEW_TASK Label

Configuration form:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.open.android.task5">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <activity android:name="SecondActivity" />
    </application>

</manifest>

Explain:

In this example, there are two MainActivities and EcondActivities.

Use cases:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.button).
                setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
            }
        });
        Log.i("maweiqi", "onCreate: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());
    }
    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        Log.i("maweiqi", "onNewIntent: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());

    }
}

Note that the jump Intent adds the FLAG_ACTIVITY_NEW_TASK flag.

public class SecondActivity extends AppCompatActivity {

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        Button button = (Button) findViewById(R.id.button2);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(SecondActivity.this, MainActivity.class);
                startActivity(intent);
            }
        });
        Log.i("maweiqi", "onCreate: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());
    }



    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        Log.i("maweiqi", "onNewIntent: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());

    }
}

Test method:

MainActivity–> SecondActivity –> MainActivity–> SecondActivity

The output log is as follows:

onCreate: MainActivity TaskId: 73 hasCode:195694529
onCreate: SecondActivity TaskId: 73 hasCode:54326677
onCreate: MainActivity TaskId: 73 hasCode:121740648
onCreate: SecondActivity TaskId: 73 hasCode:5761837

Execute the following command adb shell dumpsys activity from the command line, with the following output:

 Running activities (most recent first):
      TaskRecord{e3d17e2 #73 A=com.open.android.task5 U=0 sz=4}
        Run #3: ActivityRecord{a34fa00 u0 com.open.android.task5/.SecondActivity t73}
        Run #2: ActivityRecord{21172da u0 com.open.android.task5/.MainActivity t73}
        Run #1: ActivityRecord{b1e1e64 u0 com.open.android.task5/.SecondActivity t73}
        Run #0: ActivityRecord{f015a6e u0 com.open.android.task5/.MainActivity t73}

    mResumedActivity: ActivityRecord{a34fa00 u0 com.open.android.task5/.SecondActivity t73}

Test results:

1) All in the same task

2) Create all the different instances

So what if MainActivity jumps to remove FLAG_ACTIVITY_NEW_TASK? Add singleTask to the StockActivity manifest file, and the code and process are the same as before, only the manifest file configuration is posted.

The configuration is as follows:

<activity android:name="SecondActivity"
            android:launchMode="singleTask"/>

Test method:

MainActivity–> SecondActivity –> MainActivity–> SecondActivity

The output log is as follows:

onCreate: MainActivity TaskId: 74 hasCode:195694529
onCreate: SecondActivity TaskId: 74 hasCode:54326677
onCreate: MainActivity TaskId: 74 hasCode:38155814
onNewIntent: SecondActivity TaskId: 74 hasCode:54326677

Execute the following command adb shell dumpsys activity from the command line, with the following output:

   Running activities (most recent first):
      TaskRecord{46d0de2 #74 A=com.open.android.task5 U=0 sz=2}
        Run #1: ActivityRecord{b31602f u0 com.open.android.task5/.SecondActivity t74}
        Run #0: ActivityRecord{f88d9dc u0 com.open.android.task5/.MainActivity t74}

    mResumedActivity: ActivityRecord{b31602f u0 com.open.android.task5/.SecondActivity t74}

Test results:

1) The effects of FLAG_ACTIVITY_NEW_TASK and singleTask have different effects.

What if the android: task Affinity of the two activities are different? What effect will this lead to? Next, let's take an example to see the effect.

The configuration is as follows:

<activity android:name="SecondActivity"
                  android:taskAffinity="com.maweiqi.second"/>

The code goes back to the original MainActivity or adds Flag tags. Other omissions are as follows:

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.button).
                setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                startActivity(intent);
            }
        });
        Log.i("maweiqi", "onCreate: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());
    }
    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

        Log.i("maweiqi", "onNewIntent: " + getClass().getSimpleName() +
                " TaskId: " + getTaskId() + " hasCode:" + this.hashCode());

    }
}

Test method:

MainActivity–> SecondActivity –> MainActivity–> SecondActivity

The output log is as follows:

onCreate: MainActivity TaskId: 77 hasCode:195694529
onCreate: SecondActivity TaskId: 78 hasCode:54326677
onCreate: MainActivity TaskId: 78 hasCode:38155814

Execute the following command adb shell dumpsys activity from the command line, with the following output:

Running activities (most recent first):
      TaskRecord{65dda1d #78 A=com.maweiqi.second U=0 sz=2}
        Run #2: ActivityRecord{845c9ed u0 com.open.android.task5/.MainActivity t78}
        Run #1: ActivityRecord{f813328 u0 com.open.android.task5/.SecondActivity t78}
      TaskRecord{dd8e492 #77 A=com.open.android.task5 U=0 sz=1}
        Run #0: ActivityRecord{7a85f99 u0 com.open.android.task5/.MainActivity t77}

    mResumedActivity: ActivityRecord{845c9ed u0 com.open.android.task5/.MainActivity t78}

Test results:

1) When we enter MainActivity for the second time and attempt to enter Second Activity from MainActivity, it has no effect and still remains in MainActivity. That is, the second MainActivity --> Second Activity never happened at all!

Result analysis:

1) When the android: task Affinity of the two activities that jump over each other is different, add FLAG_ACTIVITY_NEW_TASK: When the second activity is first started, a new task is created and the second activity is added to the task. This is the same effect as singleTask! But nothing happened when an attempt was made to re-enter Second Activity from MainActivity!

2) Why? Because the Second Activity instance already exists at this time, but the top of the task stack is MainActivity; and adding FLAG_ACTIVITY_NEW_TASK alone will not "delete the activity instance above the Second Activity" in the task, so there is no jump!

Let's add FLAG_ACTIVITY_CLEAR_TOP and see the effect again.

Modify the click events in MainActivity as follows:

Intent intent = new Intent(MainActivity.this, SecondActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK 
                        | Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);

<activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
<activity android:name="SecondActivity"/>

Test method:

MainActivity–> SecondActivity –> MainActivity–> SecondActivity

Log Output

onCreate: MainActivity TaskId: 80 hasCode:58656936
onCreate: SecondActivity TaskId: 80 hasCode:212434303
onCreate: MainActivity TaskId: 80 hasCode:121740648
onCreate: SecondActivity TaskId: 80 hasCode:15009890

Test results:

1) MainActivity and EcondActivity are in the same task!

2) Two Second Activities are different instances.

Result analysis:

This is the same as without adding FLAG_ACTIVITY_CLEAR_TOP! This means that when two activities jump each other's android: task Affinity is the same, it will not produce any effect!

Next, take a look at the different Android: task Affinity scenarios. The code is consistent and the manifest file is modified.

File configuration

<activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
<activity android:name="SecondActivity"
                  android:taskAffinity="com.maweiqi.second"/>

Test method:

MainActivity–> SecondActivity –> MainActivity–> SecondActivity

Log Output

onCreate: MainActivity TaskId: 83 hasCode:195694529
05-18 05:38:11.757 6974-6974/com.open.android.task5 I/maweiqi: onCreate: SecondActivity TaskId: 84 hasCode:54326677
05-18 05:38:12.988 6974-6974/com.open.android.task5 I/maweiqi: onCreate: MainActivity TaskId: 84 hasCode:190178689
05-18 05:38:13.965 6974-6974/com.open.android.task5 I/maweiqi: onCreate: SecondActivity TaskId: 84 hasCode:5761837

Test results:

1) MainActivity and EcondActivity are in different task s!

2) Two Second Activities are different instances.

Result analysis:

The use of FLAG_ACTIVITY_NEW_TASK and FLAG_ACTIVITY_CLEAR_TOP is related to android: task Affinity.
In the case of using FLAG_ACTIVITY_NEW_TASK|FLAG_ACTIVITY_CLEAR_TOP at the same time, start B with A

1) When taskAffinity of A and B is the same, adding FLAG_ACTIVITY_NEW_TASK|FLAG_ACTIVITY_CLEAR_TOP has no effect. The effect is the same as when no additions are made!

2) When taskAffinity of A and B is different: adding FLAG_ACTIVITY_NEW_TASK|FLAG_ACTIVITY_CLEAR_TOP, the performance is the same as that of B singleTask!

Keywords: Android shell xml encoding

Added by Stephen68 on Sun, 30 Jun 2019 04:14:17 +0300

Programming VIP

What are the activation modes of activity? What does it mean? (three)

Configuration form:

Explain:

Use cases:

Test method:

The output log is as follows:

Execute the following command adb shell dumpsys activity from the command line, with the following output:

Test results:

The configuration is as follows:

Test method:

The output log is as follows:

Execute the following command adb shell dumpsys activity from the command line, with the following output:

Test results:

The configuration is as follows:

Test method:

The output log is as follows:

Execute the following command adb shell dumpsys activity from the command line, with the following output:

Test results:

Result analysis:

Let's add FLAG_ACTIVITY_CLEAR_TOP and see the effect again.

Test method:

Log Output

Test results:

Result analysis:

File configuration

Test method:

Log Output

Test results:

Result analysis:

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